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Researchers agree that the ideal scaffold for tissue engineering should possess a 3D and highly porous structure, biocompatibility to encourage cell/tissue growth, suitable surface chemistry for cell attachment and differentiation, and mechanical properties that match those of the surrounding tissues. However, there is no consensus on the optimal pore distribution. In this study, we investigated the effect of pore distribution on corrosion resistance and performance of human mesenchymal stem cells (hMSC) using titanium scaffolds fabricated by laser beam powder bed fusion (PBF-LB). We designed two scaffold architectures with the same porosities (i.e., 75 %) but different distribution of pores of three sizes (200, 500, and 700 µm). The pores were either grouped in three zones (graded, GRAD) or distributed randomly (random, RAND). Microfocus X-ray computed tomography revealed that the chemically polished scaffolds had the porosity of 69 ± 4 % (GRAD) and 71 ± 4 % (RAND), and that the GRAD architecture had the higher surface area (1580 ± 101 vs 991 ± 62 mm2) and the thinner struts (221 ± 37 vs 286 ± 14 µm). The electrochemical measurements demonstrated that the apparent corrosion rate of chemically polished GRAD scaffold decreased with the immersion time extension, while that for polished RAND was increased. The RAND architecture outperformed the GRAD one with respect to hMSC proliferation (over two times higher although the GRAD scaffolds had 85 % higher initial cell retention) and migration from a monolayer. Our findings demonstrate that the pore distribution affects the biological properties of the titanium scaffolds for bone tissue engineering.
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Células Madre Mesenquimatosas , Ingeniería de Tejidos , Andamios del Tejido , Titanio , Titanio/química , Humanos , Andamios del Tejido/química , Porosidad , Células Madre Mesenquimatosas/citología , Corrosión , Ingeniería de Tejidos/métodos , Proliferación Celular , Ensayo de Materiales , Materiales Biocompatibles/químicaRESUMEN
We searched for antideuterons (d[over ¯]'s) in the 4.7×10^{9} cosmic-ray events observed during the BESS-Polar II flight at solar minimum in 2007-2008 but found no candidates. The resulting 95% C.L. upper limit on the d[over ¯] flux is 6.7×10^{-5} (m^{2} s sr GeV/n)^{-1} in an energy range from 0.163 to 1.100 GeV/n. The result has improved by more than a factor of 14 from the upper limit of BESS97, which had a potential comparable to that of BESS-Polar II in the search for cosmic-origin d[over ¯]'s and was conducted during the former solar minimum. The upper limit of d[over ¯] flux from BESS-Polar II is the first result achieving the sensitivity to constrain the latest theoretical predictions.
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Objective: The transjugular or transfemoral approach is used as a common method for hepatic venous pressure gradient (HVPG) measurement in current practice. This study aims to confirm the safety and effectiveness of measuring HVPG via the forearm venous approach. Methods: Prospective recruitment was conducted for patients with cirrhosis who underwent HVPG measurement via the forearm venous approach at six hospitals in China and Japan from September 2020 to December 2020. Patients' clinical baseline information and HVPG measurement data were collected. The right median cubital vein or basilic vein approach for all enrolled patients was selected. The HVPG standard process was used to measure pressure. Research data were analyzed using SPSS 22.0 statistical software. Quantitative data were used to represent medians (interquartile ranges), while qualitative data were used to represent frequency and rates. The correlation between two sets of data was analyzed using Pearson correlation analysis. Results: A total of 43 cases were enrolled in this study. Of these, 41 (95.3%) successfully underwent HVPG measurement via the forearm venous approach. None of the patients had any serious complications. The median operation time for HVPG detection via forearm vein was 18.0 minutes (12.3~38.8 minutes). This study confirmed that HVPG was positively closely related to Child-Pugh score (r = 0.47, P = 0.002), albumin-bilirubin score (r = 0.37, P = 0.001), Lok index (r = 0.36, P = 0.02), liver stiffness (r = 0.58, P = 0.01), and spleen stiffness (r = 0.77, P = 0.01), while negatively correlated with albumin (r = -0.42, P = 0.006). Conclusion: The results of this multi-centre retrospective study suggest that HVPG measurement via the forearm venous approach is safe and feasible.
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Hipertensión Portal , Humanos , Hipertensión Portal/complicaciones , Estudios Retrospectivos , Estudios Prospectivos , Antebrazo , Cirrosis Hepática/complicaciones , Presión Portal , Albúminas , Presión VenosaRESUMEN
INTRODUCTION: To compare CT (computed tomography) values for enhancement of the abdominal aorta and liver parenchyma during dynamic contrast enhancement (CE) CT in cirrhotic patients with and without splenomegaly (SM). METHODS: We considered 258 patients (83 males and 46 females for the splenomegaly group, and 83 males and 46 females for the control group) for this retrospective study. We measured CT values in the abdominal aorta and hepatic parenchyma during the hepatic arterial (HAP) and portal venous (PVP) phases. The aortic CE at HAP and the hepatic parenchymal CE at PVP were compared between the two groups. For success rate of scans, we also calculated the optimal CE rates (>280 HU in the abdominal aorta and >50 HU in the hepatic parenchyma) for each group. RESULTS: In the SM group, the CE for abdominal aorta was decreased during the aortic phase for a dynamic CE-CT (p < 0.05). When evaluating the success rates, they were found to be 65.1 % and 58.9 % in the SM group and 81.4 % and 72.3 % in the non-SM group (p < 0.05). CONCLUSION: The success rate of scans and CE for the abdominal aorta during the aortic phase exhibited a significant decrease during dynamic CE-CT scans on patients with SM. Patients with SM may have reduced diagnostic ability with typical contrast injection protocols. IMPLICATIONS FOR PRACTICE: It may be necessary to change the injection rates and contrast medium volume during CE-CT depending on the presence or absence of SM.
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Medios de Contraste , Esplenomegalia , Masculino , Femenino , Humanos , Estudios Retrospectivos , Esplenomegalia/diagnóstico por imagen , Cirrosis Hepática/complicaciones , Cirrosis Hepática/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodosRESUMEN
BACKGROUND: In older people, frailty has been recognized as an important prognostic factor. However, only a few studies have focused on multidimensional frailty as a predictor of mortality and readmission among inpatients with pneumonia. OBJECTIVE: The present study aimed to assess the association between preadmission frailty and clinical outcomes after the hospitalization of older patients with pneumonia. DESIGN: Single-center, retrospective case-control study. SETTING: Acute phase hospital at Kobe, Japan. PARTICIPANTS: The present study included 654 consecutive older inpatients with pneumonia. MEASUREMENTS: Frailty status before admission was assessed using total Kihon Checklist (KCL) score, which has been used as a self-administered questionnaire to assess comprehensive frailty, including physical, social, and cognitive status. The primary outcome was a composited 6-month mortality and readmission after discharge. RESULTS: In total, 330 patients were analyzed (median age: 79 years, male: 70.4%, median total KCL score: 10 points), of which 68 were readmitted and 10 died within 6 months. After multivariate analysis, total KCL score was associated with a composited 6-month mortality and readmission (adjusted hazard ratio, 1.07; 95% confidence interval, 1.02-1.12; p = 0.006). The cutoff value for total KCL score determined by receiver operating characteristic curve analysis was 15 points (area under the curve = 0.610). The group with a total KCL score ≥ 15 points had significantly higher readmission or mortality rates than the groups with a total KCL score < 15 points (p < 0.001). CONCLUSIONS: Preadmission frailty status in older patients with pneumonia was an independent risk factor for readmission and survival after hospitalization.
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Fragilidad , Neumonía , Humanos , Masculino , Anciano , Fragilidad/diagnóstico , Anciano Frágil , Readmisión del Paciente , Estudios Retrospectivos , Estudios de Casos y Controles , Evaluación Geriátrica/métodosRESUMEN
Exposure risk is assessed based on modeling suitable habitat of large pelagic fish and oil spill scenarios originating at three wells located in the western GM's deep waters. Since the fate of the oil depends on the oceanographic conditions present during the accident, as well as the magnitude and duration of the spill, which are not known a priori, the scenarios used are a statistical representation of the area in which oil spilled from the well could be found, given all possible outcomes. The ecological vulnerability assessment identified a subset of bony fish with low-medium vulnerability and elasmobranchs with medium-high vulnerability. The oiling probability and exposure risk of both bony fish and elasmobranchs hotspots vary by well analyzed. Thus, these results provide essential information for a risk management plan for the assessed species and others with economic or conservation importance distributed in the GM and worldwide.
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Contaminación por Petróleo , Animales , Ecosistema , Peces , Golfo de México , ProbabilidadRESUMEN
In 2000, an equine Yamakagashi (Rhabdophis tigrinus) antivenom (Lot 0001) was testmanufactured as an unapproved drug for treatment of Yamakagashi bites. It was stocked on the premise of super-legal use from the viewpoint of emergency health crisis management. The antivenom showed a strong neutralizing ability against the hemorrhagic and coagulation activity of the Yamakagashi venom in its potency test. One vial of the antivenom can effectively neutralize at least about 4 mg of Yamakagashi venom. Its efficacy has also been confirmed in patients with severe cases of R. tigrinus bite that has been used in emergency. In 2020, this antivenom (Lot 0001) has reached 20 years after its production. To evaluate the integrity and potency of the antivenom, quality control, safety and potency tests had been conducted almost every year since 2012. Physical and chemical tests (property test, moisture content test, insoluble foreign matter test, osmotic pressure ratio test, pH test, protein content test, endotoxin test, sterility test) of the antivenom, showed no significant changes throughout the years, when compared to the results immediately after its production in 2000. All the parameters measured were also within the standard values. In animal safety tests (test for absence of toxicity and pyrogen), there was no change in the test results during the storage period and no abnormalities were observed. The potency test (anti-coagulant activity) after 20 years of the product, showed the same potency as those recorded immediately after production. Therefore, in all of the stability monitoring tests conducted so far, the product did not show any significant change compared to the results immediately after production. This confirms the stability of the product during the stockpiling period to the present, that is, 20 years after production.
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Antivenenos , Colubridae , Estabilidad de Medicamentos , Animales , Antivenenos/análisis , Almacenaje de Medicamentos , Caballos , Control de CalidadRESUMEN
AIM: Precise biomarkers for predicting prognosis could help to identify high-risk Crohn's disease (CD) patients to facilitate better follow-up during the postoperative course. In this study, the primary aim is the identification of the most reliable nutrition marker that predicts surgical relapse in CD patients. METHOD: We first evaluated the predictive value of various nutrition markers for postoperative surgical relapse in CD patients and identified the advanced lung cancer inflammation index (ALI) as a promising biomarker. Then, we assessed the clinical significance of preoperative ALI in CD patients using two cohorts. RESULTS: Preoperative ALI showed the highest correlation with reoperation rate compared with other nutritional parameters in CD patients receiving surgical resection (sensitivity 53%, specificity 86%, area under the curve 0.71). Lower levels of preoperative ALI were significantly correlated with the presence of perianal disease. A lower level of preoperative ALI was an independent prognostic factor for reoperation rate after an intestinal resection (hazard ratio 3.37, 95% CI 1.38-10.12, P = 0.006), and the prognostic impact of preoperative ALI was successfully validated in an independent cohort using the same cut-off value. CONCLUSION: Preoperative ALI might be useful for postoperative management of CD patients.
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Enfermedad de Crohn , Neoplasias Pulmonares , Enfermedad de Crohn/complicaciones , Enfermedad de Crohn/cirugía , Humanos , Inflamación , Neoplasias Pulmonares/cirugía , Recurrencia Local de Neoplasia , Estudios RetrospectivosRESUMEN
OBJECTIVE: To define the prevalence of adverse outcomes of maternal infection in a large cohort of ZIKV-infected Brazilian women and their infants. DESIGN: Prospective population-based cohort study. SETTING: Ribeirão Preto's region's private and public health facilities. POPULATION: Symptomatic ZIKV-infected mothers and their infants. METHODS: Prenatal/early neonatal data were obtained for all mother-child pairs. A subgroup of infants had cranial ultrasonography, eye fundoscopy, hearing and neurological examinations and Bayley III screening tests within 3 months of age. MAIN OUTCOME MEASURES: Prevalence of pregnancy losses and anomalies detected at birth or within 3 months according to the gestational age of infection. RESULTS: Overall, 511 ZIKV-infected women were identified from a total of 1116 symptomatic women; as there were two twins, there were a total of 513 fetuses included. Of these, 13 (2.5%; 95% CI 1.5-4.3) presented with major signs of congenital Zika syndrome (CZS). Of the 511 women, there were 489 livebirths and 24 (4.7%) pregnancy losses (20 miscarriages and four stillbirths). ZIKV-related anomalies occurred in the offspring of 42/511 (8.2%) mothers. Microcephaly or other CNS malformations were diagnosed in 1/4 (25.0%) stillbirths and in 19/489 (3.9%; 95% CI 2.5-5.9) of the liveborn infants. Fetal abnormalities were 14.0 (95% CI 7.6-26.0) times more likely with gestational infection occurring in ≤11 weeks. On follow up of 280 asymptomatic infants, 2/155 (1.3%) had eye abnormalities, 1/207 (0.5%) had CNS imaging findings and 16/199 (8%) presented neurological alert signs. CONCLUSIONS: This prospective population-based study represents the largest Brazilian cohort study of ZIKV in pregnancy. Congenital anomalies potentially associated with CZS are less frequent than previously thought. There is a strong association between the gestational age of infection (≤11 weeks) and a poorer early infant prognosis. A notable proportion of apparently asymptomatic newborns can present with subclinical findings within 3 months of age. TWEETABLE ABSTRACT: ZIKV and pregnancy: adverse outcomes are less common, more prevalent for first-trimester infections, and potentially subclinical.
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Malformaciones del Sistema Nervioso/epidemiología , Complicaciones Infecciosas del Embarazo/virología , Infección por el Virus Zika/complicaciones , Adulto , Brasil , Estudios de Cohortes , Femenino , Edad Gestacional , Humanos , Recién Nacido , Masculino , Embarazo , Complicaciones Infecciosas del Embarazo/diagnóstico , Resultado del Embarazo , Prevalencia , Factores de Riesgo , Infección por el Virus Zika/diagnósticoRESUMEN
INTRODUCTION: The morphologic changes in the compensated stage of liver cirrhosis (cLC) are not diffuse atrophic changes. With cLC lobar or segmental changes combined with atrophy of the right lobe and medial segment together with hypertrophy of the caudate lobe and lateral segment are commonly seen. The purpose of this study was to evaluate the morphologic changes in hepatitis virus-related liver cirrhosis in relationship to haemodynamics of the portal vein on dynamic contrast-enhanced computed tomography (DCE-CT) METHODS: This study included 72 patients, 46 with hepatitis virus-related cirrhosis and 26 with a normally functioning liver, who underwent DCE-CT. In cirrhosis patients, the morphologic change index (MCI) of the liver was calculated and categorised into two groups, high-MCI (MCI ≥ 0.4) (n = 21) and low-MCI (MCI < 0.4) (n = 25). Cross-sectional areas of the main, right and left portal veins and the intra-portal distribution from splenic venous flow were evaluated for their relationships with the MCI and compared among three groups (normal-control, low MCI and high MCI). RESULTS: There was a significant difference in the cross-sectional area of the left portal vein between the high-MCI group and the low-MCI group (p = 0.013) and the control group (p = 0.008). A significant correlation was identified between the cross-sectional area of the left portal vein and the MCI (r = 0.508, p < 0.001). CONCLUSION: Cross-sectional area of the left portal vein may be a factor related to morphologic changes in hepatitis virus-related liver cirrhosis and could be a possible index of the left portal venous flow volume. IMPLICATIONS FOR PRACTICE: This study may be useful for predicting the degree of hepatic morphologic changes and the condition of cirrhosis in association with regional hepatic morphologic changes.
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Cirrosis Hepática , Vena Porta , Hemodinámica , Virus de Hepatitis , Humanos , Cirrosis Hepática/diagnóstico por imagen , Vena Porta/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
@#In 2000, an equine Yamakagashi (Rhabdophis tigrinus) antivenom (Lot 0001) was testmanufactured as an unapproved drug for treatment of Yamakagashi bites. It was stocked on the premise of super-legal use from the viewpoint of emergency health crisis management. The antivenom showed a strong neutralizing ability against the hemorrhagic and coagulation activity of the Yamakagashi venom in its potency test. One vial of the antivenom can effectively neutralize at least about 4 mg of Yamakagashi venom. Its efficacy has also been confirmed in patients with severe cases of R. tigrinus bite that has been used in emergency. In 2020, this antivenom (Lot 0001) has reached 20 years after its production. To evaluate the integrity and potency of the antivenom, quality control, safety and potency tests had been conducted almost every year since 2012. Physical and chemical tests (property test, moisture content test, insoluble foreign matter test, osmotic pressure ratio test, pH test, protein content test, endotoxin test, sterility test) of the antivenom, showed no significant changes throughout the years, when compared to the results immediately after its production in 2000. All the parameters measured were also within the standard values. In animal safety tests (test for absence of toxicity and pyrogen), there was no change in the test results during the storage period and no abnormalities were observed. The potency test (anti-coagulant activity) after 20 years of the product, showed the same potency as those recorded immediately after production. Therefore, in all of the stability monitoring tests conducted so far, the product did not show any significant change compared to the results immediately after production. This confirms the stability of the product during the stockpiling period to the present, that is, 20 years after production.
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OBJECTIVE: Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease characterized by progressive cartilage degeneration, abnormal bone remodeling, and chronic pain. In this study, we aimed to investigate effective therapies to reverse or suppress TMJOA progression. DESIGN: To this end, we performed intravenous administration of serum free conditioned media from human exfoliated deciduous teeth stem cells (SHED-CM) into a mechanical-stress induced murine TMJOA model. RESULTS: SHED-CM administration markedly suppressed temporal muscle inflammation, and improved bone integrity and surface smoothness of the destroyed condylar cartilage. Moreover, SHED-CM treatment decreased the number of IL-1ß, iNOS, and MMP-13 expressing chondrocytes, whereas it specifically increased PCNA-positive cells in the multipotent polymorphic cell layer. Notably, the numbers of TdT-mediated dUTP nick end labeling (TUNEL)-positive apoptotic chondrocytes in the SHED-CM treated condyles were significantly lower than in those treated with DMEM, whereas the proteoglycan positive area was restored to a level similar to that of the sham treated group, demonstrating that SHED-CM treatment regenerated the mechanical-stress injured condylar cartilage and subchondral bone. Secretome analysis revealed that SHED-CM contained multiple therapeutic factors that act in osteochondral regeneration. CONCLUSIONS: Our data demonstrated that SHED-CM treatment promoted the regeneration and repair of mechanical-stress induced mouse TMJOA. Our observations suggest that SHED-CM has potential to be a potent tissue-regenerating therapeutic agent for patients with severe TMJOA.
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Productos Biológicos/metabolismo , Productos Biológicos/uso terapéutico , Pulpa Dental/citología , Osteoartritis/terapia , Células Madre/metabolismo , Articulación Temporomandibular , Animales , Modelos Animales de Enfermedad , Humanos , Masculino , RatonesRESUMEN
BACKGROUND: Surgery is the gold standard for basal cell carcinomas (BCC). Current recommended surgical margins for BCCs are determined from studies in Caucasian populations. However, the appropriate surgical margins for BCCs in non-white races are unclear. OBJECTIVES: To investigate the accuracy of preoperative determination of clinical tumour borders and appropriate surgical margins in Japanese patients with BCC. METHODS: The maximum calculated differences in distance between the preoperatively determined surgical margins and the actual histologic tumour side margins were considered as 'accuracy gaps' of clinical tumour borders. Estimated side margin positivity rates (ESMPRs) with narrower (2 and 3 mm) surgical margins were calculated on the basis of the accuracy gaps. RESULTS: Overall, 1000 surgically excised BCCs from 980 Japanese patients were included. The most frequent histologic subtype was nodular BCC (67%). The median accuracy gap was 0.3 mm [interquartile range (IQR): -0.5 to +1 mm]. The ESMPRs with 2- and 3-mm surgical margins were 3.8% and 1.4%, respectively. Only the ESMPRs between the well-defined (n = 921) and poorly defined clinical tumour border groups (n = 79) showed statistical difference [2-mm margin: 3.1% vs. 11.7%, OR: 3.89, 95% confidential interval (CI): 1.41-10.71, P <0.01; 3-mm margin: 0.97% vs. 6.3%, OR: 6.58, 95% CI: 1.67-25.99, P <0.01]. No significant differences in ESMPRs were noted in other subgroups including risk classifications. CONCLUSIONS: The determined clinical tumour border accuracy gaps in this Japanese cohort were negligible. Dermatologic surgeons may use narrower surgical margins with acceptable margin positivity rates. The clarity of clinical tumour borders could be an appropriate guide for selection of different surgical margins in the Japanese cohort.
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Carcinoma Basocelular , Neoplasias Cutáneas , Carcinoma Basocelular/cirugía , Humanos , Japón , Márgenes de Escisión , Estudios Retrospectivos , Neoplasias Cutáneas/cirugíaAsunto(s)
Anticuerpos Monoclonales Humanizados/efectos adversos , Antineoplásicos/efectos adversos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/radioterapia , Radiodermatitis/inducido químicamente , Anciano , Humanos , MasculinoRESUMEN
Recent studies show that the ozone layer will recover by the middle part of this century. This is a significant result arising from the Montreal Protocol, and highlights the success of this environmental protection agreement. Climate change projections show that Total Ozone Content (TOC) levels will increase significantly by the end of this century, mainly at higher latitudes. This increase may result in a reduction of the adverse effects of UV radiation overexposure. By contrast, reduced UV radiation levels at the surface of the Earth can result in reduced levels of vitamin D synthesis among the inhabitants of these regions. In this study we provide estimates for the UVI, erythemal, and vitamin-D weighted daily doses for ten different locations in South America and Antarctica. Our calculations were based on ozone projections provided by climate models set forth in the last IPCC report. Results show that the increase of TOC levels in middle and high latitude regions may result in decreased UVI and UV doses throughout the century. In high latitudes, erythemal doses and vitamin D synthesis doses may be reduced by up to 22 and 39%, respectively, if anthropogenic emissions continue to rise throughout the century. Furthermore, there may be reductions of up to 9 and 12%, respectively, in mid-latitudes (20°S to 35°S). Significant variations at Equatorial sites were not observed. In most of South America, the attenuation in UVR caused by increases in TOC during the 21st century is neither enough to promote protective effects from this radiation, nor for the lack of UVR for vitamin D synthesis. The incidence of UVR in tropical and sub-tropical areas of the continent will continue to be a public health risk for the entire 21st century during all seasons, regardless of the climatic scenarios. Our results can be used as an important tool for health studies focusing on the excess and/or lack of sun exposure.
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Eritema/etiología , Ozono/química , Rayos Ultravioleta , Vitamina D/biosíntesis , Regiones Antárticas , Humanos , Estaciones del Año , América del Sur , Rayos Ultravioleta/efectos adversosRESUMEN
The pseudogap phenomenon in the cuprates is arguably the most mysterious puzzle in the field of high-temperature superconductivity. The tetragonal cuprate HgBa2CuO4+δ, with only one CuO2 layer per primitive cell, is an ideal system to tackle this puzzle. Here, we measure the magnetic susceptibility anisotropy within the CuO2 plane with exceptionally high-precision magnetic torque experiments. Our key finding is that a distinct two-fold in-plane anisotropy sets in below the pseudogap temperature T*, which provides thermodynamic evidence for a nematic phase transition with broken four-fold symmetry. Surprisingly, the nematic director orients along the diagonal direction of the CuO2 square lattice, in sharp contrast to the bond nematicity along the Cu-O-Cu direction. Another remarkable feature is that the enhancement of the diagonal nematicity with decreasing temperature is suppressed around the temperature at which short-range charge-density-wave formation occurs. Our result suggests a competing relationship between diagonal nematic and charge-density-wave order in HgBa2CuO4+δ.
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The maximum-likelihood expectation maximization (ML-EM) method is expected to improve the accuracy of airborne radiation monitoring using an unmanned aerial vehicle. The accuracy of the ML-EM method depends on various parameters, including detector efficiency, attenuation factor, and shielding factor. In this study, we evaluate the shielding factor of trees based on several field radiation measurements. From the actual measurement, the shielding factors were well correlated with the heights of the trees. The evaluated shielding factors were applied to the ML-EM method in conjunction with the measured data obtained from above the Fukushima forest. Compared with the conventional methods used for calculating the dose rate, the proposed method is found to be more reliable.
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Contaminantes Radiactivos del Aire/análisis , Algoritmos , Accidente Nuclear de Fukushima , Funciones de Verosimilitud , Monitoreo de Radiación/métodosRESUMEN
As-Based Zintl compounds Ba1-xKxCd2As2 crystallized in the CaAl2Si2-type structure (space group P3[combining macron]m1) were prepared using solid-state reactions followed by hot-pressing. We have successfully substituted K for Ba up to x = 0.08, producing hole-carrier doping with concentrations up to 1.60 × 1020 cm-3. We have determined the band-gap value of non-doped BaCd2As2 to be 0.40 eV from the temperature dependence of the electrical resistivity. Both the electrical resistivity and the Seebeck coefficient decrease with hole doping, leading to a power factor value of 1.28 mW m-1 K-2 at 762 K for x = 0.04. A first-principles band calculation shows that the relatively large power factor mainly originates from the two-fold degeneracy of the bands comprising As px,y orbitals and from the anisotropic band structure at the valence-band maximum. The lattice thermal conductivity is suppressed by the K doping to 0.46 W m-1 K-1 at 773 K for x = 0.08, presumably due to randomness. The effect of randomness is compensated by an increase in the electronic thermal conductivity, which keeps the total thermal conductivity approximately constant. In consequence, the dimensionless figure-of-merit ZT reaches a maximum value of 0.81 at 762 K for x = 0.04.